The present invention relates to a rotating electric machine such as a turbine generator.
A cylindrical rotor of a rotating electric machine such as a conventional turbine generator is provided with a magnetic winding, which excites the generator when the rotor receives a DC current from an exciting power source.
The rotor is provided with a plurality of slots for inserting magnetic windings therein at equally spaced intervals in the circumferential direction thereof, and teeth are installed between the slots. Within each slot, the magnetic winding is disposed in layers and held. When the magnetic winding is energized, the temperature of the conductor may sometimes rise to not less than 100.degree. C. Therefore, in order to prevent a decrease in the strength of a resin material for electric insulation, as in an example described in JP-A-60-190135 and an example described in JP-A-9-285052, a plurality of gas vent holes are provided in the magnetic winding in the lamination direction thereof and a gas, such as air and hydrogen gas, is caused to flow through these holes, thereby cooling the conductor. In order to vent this gas in the radial direction of the rotor, gas vent holes with a size larger than those provided in the magnetic winding are formed in a creepage block for electric insulation and in wedges for fixing the magnetic winding and the creepage block. The holes in the magnetic winding have a shape of an ellipse that is long in the axial direction of the rotor and, therefore, in order to cause the gas to flow with efficiency, a gas vent groove with a cross section of a circular arc or a rectangular cross section, is formed in a continuous shape in the axial direction of the rotor on the face of a creepage block abutting against the magnetic winding, thereby providing a passage of the cooling gas. Usually, this gas vent groove is simultaneously machined (cut) when a creepage block is cut from a glass-reinforced epoxy resin plate.
In a rotating electric machine such as a turbine generator, the operating temperature of a magnetic winding is apt to rise in association with large capacity design of the rotating machine, causing the problems of the necessity for improving the cooling capacity and the necessity for keeping the strength of a resin material for insulation.